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Detailed Reference Information |
Walsh, J.E. and Portis, D.H. (1999). Variations of precipitation and evaporation over the North Atlantic Ocean, 1958–1997. Journal of Geophysical Research 104: doi: 10.1029/1999JD900189. issn: 0148-0227. |
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The output from recent atmospheric reanalysis projects at the National Centers for Environmental Prediction and the European Center for Medium-Range Weather Forecasts is used to address regional and temporal variability of precipitation P and evaporation E over the North Atlantic. The difference between P and E is the net surface freshwater flux, which directly affects the salinity and hence the stratification of the ocean surface layer. Over North Atlantic subregions, spanning 10¿--15¿ latitude and 30¿--40¿ longitude, the area-averaged P from the two reanalyses are highly correlated with each other outside of the tropics and are consistent with climatologies compiled from ship data. In the annual mean, P exceeds E in the North Atlantic poleward of 50 ¿N; E exceeds P between 20 ¿N and 50 ¿N and also in the eastern tropical North Atlantic (10 ¿N--35 ¿N). Seasonality varies considerably among the subregions: P and E both peak during late autumn/early winter in the subpolar regions, and P has an autumn peak in the subtropics, where E shows little seasonality. The year-to-year variations of monthly and annual regional values are larger for P than for E, implying that the interannual variations of P minus E are driven primarily by P. These interannual variations are sufficiently large and persistent that they can account for substantial portions (0.1--1.0 salinity unit (SU) per year) of observed salinity variations in the North Atlantic surface waters. Atmospheric forcing of regional P shows consistent teleconnections throughout the year, although the patterns are strongest in winter and weakest in summer. The North Atlantic Oscillation (NAO) is the dominant pattern controlling P in the eastern and northern North Atlantic; P in the western North Atlantic shows associations with the atmospheric circulation as far away as the North Pacific. P anomalies of >3 cm month-1 are associated with multiyear periods of positive and negative NAO. The high-NAO regime of the late 1980s and early 1990s has coincided with increased P over the northeastern North Atlantic and decreased P over the southwestern North Atlantic although the seasonality of the NAO impact varies widely among the regions. ¿ 1999 American Geophysical Union |
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Abstract |
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Keywords
Hydrology, Hydrologic budget, Hydrology, Evapotranspiration, Hydrology, Precipitation, Information Related to Geographic Region, Atlantic Ocean, Atmospheric Composition and Structure, Middle atmosphere—composition and chemistry |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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